Modification of 6,6-Type Polyamide Containing both γ-Lactone Ring and Hydrophilic Groups

Abstract

The interfacial polycondensation of (2R*,4S*)-4-chloroformyl-2-chloroformyl-methyl-2,4-dimethyl-4-butanolide (BC) with 1,6-hexanediamine (HDA) gives an unique 6,6-type polyamide (PA-6L) with partial hydrolytic cleavage of the lactone moiety. PA-6L containing at random both γ-lactone ring and hydrophilic groups such as carboxyl and hydroxyl groups was modified by the following three methods: 1) ring-opening of the lactone groups in PA-6L by chemical treatment, 2) incorporation of nylon-66 (PA-66) sequence into PA-6L chain by interfacial copolycondensation, and 3) crosslinking of PA-6L with methylene bis(4-phenylisocyanate) (MDI). The ring-opening ratio of PA-6L increased by treating with either acids or alkalis, whereas [η] decreased. In particular, the carboxylato-containing PA-6L prepared by the treatment with potassium hydroxide was highly soluble in water. In the interfacial copolycondensation of acid dichlorides, BC and adipoyl chloride (AC), with HDA, a methanol-soluble copolyamide PA-6L/66 was prepared at an [AC]/([BC]+[AC]) mole fraction of ca. 0.25. PA-6L crosslinked with MDI had a decomposition point of 303°C and showed a lower thermostability beyond 280°C than the original one.